At the present time, the most advanced method of making reinforced concrete walls and similar structural elements, uses 3D prefabricated construction modules comprising parallel panels spaced from each other. The modules also include transverse elements in the form of grids or meshes preferably horizontally oriented and fixed to the panels, and include connectors joining transverse elements and panels. The transverse elements usually have stopping details, which usually serve as support for panels. These 3D prefabricated construction modules can be made at a location remote from the construction site or directly on the site where they are eventually installed in the location desired for the building of wall or other structural elements.
The 3D prefabricated construction modules can be longitudinally and vertically interconnected to provide a continuous form in the space between a series of interconnected pairs of panels. This form space can be filled with unhardened concrete then allowed to harden to produce a structural element such as a wall. Typically the panels remain in place after the concrete has hardened and the panels provide added qualities for the structure as a whole, including providing sound and heat insulation. The panels may themselves thereafter be covered on their outward facing surfaces with a protective covering layer such as drywall, cement board, plaster, stucco and so on.
It is common for the panels to be made of lightweight materials such as foamed plastics (eg. foamed polystyrene).
There are numerous criteria to be concerned about in the design of such 3D prefabricated construction modules. For example, the 3D prefabricated module usually must be able to support appropriate reinforcement members (eg. rebar), including usually both horizontal and vertical reinforcement members. To date, most of the known designs for reinforcement support are complex and costly to implement.
Also, it should be noted, that there is a high consumption of labor when connecting 3D prefabricated construction modules and reinforcement member (ie. rebar) extensions from concrete structures beneath the modules, such as foundations, in order to provide continuous reinforcement. In most of the building systems using 3D prefabricated construction modules, installation is performed in a way akin to a “shish kebob” rodding.
Another design criterion for such 3D prefabricated modules is the requirement of both panels and the stabilizing or bracing members, to be able to withstand the relatively high hydrostatic pressures that can develop when the form is filled with unhardened concrete. Additionally, it is desirable to minimize the extent of the thermal bridge that can be created between one side of the 3D prefabricated construction module and the other, or between the inner form space and the external side of the 3D prefabricated construction module by such components as the stabilizing members. Furthermore, the technique of concrete placement itself and its further hardening allows the creation of a 3D pattern on the surface of the concreted structures. Thus, it is also desirable to have a module with at least one panel, which would have a negative pattern. After concrete hardening the panels could easily be removed leaving positive 3D pattern on the surface of the concreted structure.
Other design criteria include the desirability of having modules that are relatively easy to: inter-connect to each other; secure to supporting elements such as footings; and be easily transported to a construction site. It is also desirable to have 3D prefabricated construction modules that can be readily put into operation without a large amount of time and cost being expended.
Also, a particular concern regarding fire proofing of a structural element arises when plastic materials are used as materials for the panels and are retained on the structural element after it has been created. It is well known that fire and its associated heat can have a negative impact on structural stability of a concrete wall, and on the ability of the wall or other element to contain the fire. There is a tendency of such panels to melt when subjected to heat on one side of a wall caused by a fire in the vicinity of the wall. The liquid material from the panel then can flow toward the fire source and ignite. This can cause the fire to move along a path directly toward the wall and can create an intense fire situation right at or in the immediate vicinity of the wall. This of course has an extremely detrimental effect, both on the structural stability of the wall, as well as its ability to contain the fire. Accordingly, it is desirable to minimize the potential damage that can be done by the panels, when they are subjected to heat for a fire source.